Spatial analysis of the cereal leaf beetle (Coleoptera: Chrysomelidae) in wheat

A 2-yr study was conducted in wheat, Triticum aestivum L., in South Carolina involving weekly sampling of cereal leaf beetle, Oulema melanopus (L.). According to the Spatial Analysis by Distance IndicEs (SADIE) aggregation index, adults (80% of sampling date-field combinations) were more frequently aggregated than eggs (26%) and larvae (57%). Spatial and temporal stability, as indicated by positive association indices among sampling dates, was significant in 27, 30, 33 and 31% of analyses for adults in fields A, B, C, and D, respectively. Peak densities of adults were also spatially associated with peak densities of eggs and larvae in all fields, except for larvae in fields C and D. Spike numbers were greater in interior portions of the field compared with field edges. All stages of O. melanopus were positively associated with spike counts on at least one sampling date, generally corresponding to peak densities of each life stage. This study provides insight into the importance of wheat stand as a potential major factor influencing the spatial distribution of O. melanopus. Determining when and where O. melanopus accumulate in wheat fields in the southeastern United States can provide useful information that could lead to improved sampling plans and more efficient use of insecticides.